Washer and threaded assembly provided therewith

Abstract

A washer ( 14 ) and a threaded assembly ( 22 ) between a screw ( 30 ) and a workpiece ( 42 ) are provided. The washer ( 14 ) is offset up to an angle (α) with respect to a flat initial state, such that the washer has an insert thickness (D e ) that is substantially greater than the initial thickness (D a ) thereof. The washer ( 14 ) is made of a malleable material. The length (L g ) of an unthreaded shank section ( 40 ) of the screw ( 30 ) is smaller than the sum of the thickness (D w ) of the workpiece ( 42 ) and the insert thickness (D e ) of the washer ( 14 ), and essentially not smaller than the sum of the thickness (D w ) of the workpiece ( 14 ) and the insert thickness (D a ) of the washer ( 14 ). When the last thread of the screw ( 30 ) leaves the workpiece ( 42 ) on being screwed in, the force previously exerted on the washer ( 14 ) by the feed of the screw is zero. The washer ( 14 ) has been plastically deformed thereby, such that the washer retains the flattened state thereof and bridges the space between the workpiece ( 42 ) and the screw head ( 34 ) free from play. The workpiece ( 42 ) and the washer ( 14 ) thereby remain firmly clamped between the head ( 34 ) and the thread ( 36 ) of the screw ( 30 ), and the prevention of inverse rotation is ensured.

1. A threaded assembly comprising a screw ( 30 ) and a work piece ( 42 ), with the screw ( 30 ) having a shaft ( 30 ) provided with a thread ( 36 ) and at a free end, facing away from the head ( 34 ) having a hole-forming or hole boring tip ( 38 ) and an unthreaded shaft section ( 40 ) at its end adjacent to the head ( 34 ) and with the work piece ( 42 ) comprising at least one thin plate ( 42   a ,  42   b ), a washer ( 14 ) is arranged between the head ( 34 ) of the screw ( 30 ) and the work piece ( 42 ), with the washer ( 14 ) being provided with a bore ( 12 ) for accepting the screw ( 30 ) and which is spatially deformed around an axis ( 16 ) extending diametrically through the bore ( 12 ), the washer ( 14 ) is bent around the diametric axis ( 16 ) such that an angular crown line ( 18 ) is parallel in reference to the axis ( 16 ) and the washer ( 14 ) is angled and has an operational thickness (D e ) greater than an initial thickness (D a ) of the washer ( 14 ), and the washer ( 14 ) comprises a material selected such that the washer ( 14 ) is plastically deformed during installation, and a length (L g ) of the unthreaded shaft section ( 40 ) is smaller than a sum of a thickness (D w ) of the work piece ( 42 ) and the operational thickness (D e ) of the washer ( 14 ) and is essentially not smaller than the sum of the thickness (D w ) of the work piece ( 42 ) and the initial thickness (D a ) of the washer ( 14 ) so that play is compensated as an uppermost winding of the thread exits a bottom of a threaded bore formed by the screw in a bottom-most one of the at least one thin plate. 
     
     
       2. The threaded assembly according to  claim 1 , wherein the thread ( 36 ) of the screw ( 30 ) is self-cutting or tapping. 
     
     
       3. The threaded assembly according to  claim 1 , wherein a diameter (D g ) of the unthreaded shaft section ( 40 ) is no greater than a core diameter (D k ) of the thread ( 36 ). 
     
     
       4. The threaded assembly according to  claim 1 , wherein the shaft ( 32 ) of the screw ( 30 ) is provided with a conical connection ( 33 ) at the head ( 34 ) of the screw ( 30 ). 
     
     
       5. The threaded assembly according to  claim 4 , wherein the bore ( 12 ) of the washer ( 14 ) is at least adjusted in an unassembled state of the washer ( 14 ) to a conical connection ( 33 ) of the shaft ( 32 ).